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MG MGB Technical - Intermittent starter problem

Regarding my 79B...

I've begun to have a problem when trying to start the engine. Most of the time, it cranks and starts fine. However, sometimes when I turn the key, nothing happens. I can hear the relay making its click, but nothing from the starter. I swapped the two relays just to se if that would make a difference, and it didn't.

It's begun to happen more frequently. Then it wouldn't crank at all.

To test the solenoid, I crawled under the car and used a screwdriver to jump between the solenoid connections. The starter cranked like new. I would suspect the solenoid?

Then, just out of curiousity, I turned the ignition key, and everything worked fine. So why would bypassing the solenoid suddenly make the whole system work again?

Where is the most likely problem...the relay or solenoid? Maybe the solenoid needs to be cleaned up? Any suggestions would be appreciated. I'm afraid to leave home with it.

Thanks,
Chet
Chet Harter

Chet: On the top of this Technincal page, on the left side, there is a link "Electrical Help". Scroll down to "Starter". It has an excellent diagnostic section.
Off hand I would suspect the wiring from the relay to the solenoid, and then the solenoid.
Good Luck.
Andrew Blackley

Hmm, that reminds me. I *really* must get around to taking the new solenoid out of the boot and fitting it to the car. I'm getting fed up with having to belt the end of the starter with a tap wrench (it's a handy size and heavy) to get it to "go" every now and again. Also, I'm getting cheesed-off with the comments about unreliable old cars from the BMW*nker merchants in the company car park when they see the bonnet up, although a quick appraisal of my Insurance and running costs usually stops them in their tracks.
Double "hmmm". I've just looked out the window and it's raining. Guess I'll be putting this off again. Ho hum.
T J C Cuthill

Sounds no more and no less than an intermittent connection. It could be from the relay to the solenoid, or within the solenoid itself. As it is intermittent I'd put a temporary wire under the brown/white at the solenoid and connect the other end to a voltmeter in the cabin. If you see 12v when you turn the key the problem is in the solenoid. If no 12v it is in the wiring between relay and solenoid.
Paul Hunt

My 73 B GT had the same symptoms until it finally wouldn't turn over at all. As per Mr. Hunt's diagnosis, replaced the solenoid and cleaned up the connections and haven't had a problem since. Seems to run better, too. (I believe that there's supposed to be a rubber boot over the connection post on the solenoid, but somewhere over the decades most of ours have gone missing. Oil, grit, corrosion get in and foul things up. Just be sure to disconnect your battery cable - and clean those up, too!)
John Z

This thread was discussed between 28/06/2003 and 30/06/2003

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